No, there's nothing you can do. I'm surprised it runs at all. To put it bluntly, you can hardly expect to run any reasonably up-to-date game on an office PC like that.

The CPU is okay, but you clearly don't have enough RAM. When a program runs out of RAM its performance stalls. It's like driving a Ferrari at maximum speed and then suddenly stopping, getting out and pushing the car. We're talking access time going down from ns to ms in combination with a decrease in transfer rate.
"Not enough RAM" is never a situation one should be in.

The graphics card is completely outdated. I would have expected the game not to start at all.